In order to recover oils from certain geologic formations, injection of steam increases mobility of the oil within the formation. An example of such a process is known as steam assisted gravity drainage (SAGD). Various techniques can provide for steam generation in SAGD but with certain disadvantages.
Given quantity of the steam required for the SAGD, energy needed for the steam generation represents a substantial cost for the SAGD. In addition to the cost, other viability criteria of the steam generation for the SAGD relate to production of carbon dioxide (CO2) and water input requirements. For example, many governments regulate CO2 emissions. High costs relative to another option for the steam generation can prevent use of some options for the steam generation regardless of ability to provide desired criteria, such as with respect to the production of CO2.
Burning gas or oil to fuel burners that heat steam generating boilers creates CO2, which is a greenhouse gas that can be captured by various approaches. While further adding to the cost, capturing the CO2 from flue gases of the burners facilitates in limiting or preventing emission of the CO2 into the atmosphere. In contrast to indirect heating with the boilers, prior direct combustion processes inject steam and CO2 together into the formation even though injection of the CO2 into the formation may not be desired or acceptable in all applications.
Regarding the water input requirements, inability to recycle all of the steam injected results from having to remove impurities such as sodium chloride from any recovered water prior to the recovered water being combined with other make-up water to feed any steam generation. Limited water supplies for the make-up water at locations of where SAGD is applicable can prevent feasibility of the steam generation. Even if available, expense of purchasing water can add to cost for the SAGD.
Therefore, a need exists for improved methods and systems for steam injection and CO2 capture.